Double sink



FIG. 1 is a perspective view of the claimed design;

FIG. 2 is a top view of the claimed design;

FIG. 3 is a bottom view of the claimed design;

FIG. 4 is a right side view of the claimed design;

FIG. 5 is a left side view of the claimed design;

FIG. 6 is a front side view of the claimed design; and,

FIG. 7 is a back side view of the claimed design.

The broken lines showing in FIGS. 1-7 are for the purposes illustration and form no part of the claimed design. 

The ornamental design for a double sink, as shown and described. 